The present invention relates generally to vehicle systems and more particularly to a hydrocarbon vapor evacuation system.
Significant advances have been made in recent years in controlling the emission of hydrocarbon vapor from vehicle engines during engine-on conditions. However, a significant portion of the remaining hydrocarbon emissions from a vehicle occur after the vehicle engine is shut off. For example, hydrocarbon vapor may be produced within a vehicle""s transmission, engine coolant reservoir, washer fluid reservoir, intake air induction system, or even a vehicle""s passenger compartment during engine-off conditions.
Charcoal vapor canisters attached in series to a vehicle""s fuel storage system are used to adsorb hydrocarbon vapor produced in the fuel storage system in engine-off conditions. However, these charcoal canisters typically are not coupled to other vehicle components that may emit vapor during engine-off cycles. As such, vapor emitted from these components may be released into the atmosphere.
It is thus highly desirable to couple a vapor storage system with these various vehicle components that emit hydrocarbon vapor in engine-off conditions to prevent the emission of hydrocarbon vapor to the atmosphere.
The above object is realized by providing a hydrocarbon vapor evacuation system that couples the hydrocarbon vapor emitting components with a hydrocarbon vapor canister. A small-flow rate gas-phase pump is operated intermittently whenever the engine is shut off.
The suction side of the pump has a manifold with vapor connections to any or all of the vehicle components that potentially emit hydrocarbon vapors during the engine-off period. The pressure side of the pump is directed to the vehicle vapor canister.
A small electric motor controlled by a stand alone controller drives the pump intermittently as a function of ambient temperature, time, or both ambient temperature and time. To save the vehicle battery, the duty cycle can be reduced to zero when the state of charge of the battery is determined to be too low to maintain long battery life.
Thus, hydrocarbon vapor generated within various vehicle components is pumped into a vapor canister, wherein it is adsorbed, to prevent the emission of the hydrocarbon vapor to the atmosphere. This allows vehicles having such a system to meet zero emission standards such as the California LEV-II requirement.
Other objects and advantages of the present invention will become apparent upon considering the following detailed description and appended claims, and upon reference to the accompanying drawings.